Gamma-conopeptides

ABSTRACT

This invention relates to relatively short peptides about 25-40 residues in length, which are naturally available in minute amounts in the venom of the cone snails or analogs to the naturally available peptides, and which include three cyclizing disulfide linkages and one or more γ-carboxyglutamate residues. More specifically, the present invention is directed to γ-conopeptides having the general formula I: Xaa 1 -Cys-Xaa 2 -Cys-Xaa 3 -Xaa 4 -Cys-Cys-Xaa 5 -Cys-Xaa 6 -Cys-Xaa 7  (SEQ ID NO:1), as described herein; or having the general formula II: Xaa 1 -Cys-Xaa 2 -Cys-Xaa 3 -Xaa 4 -Cys-Cys-Xaa 5 -Xaa 6 -Cys-Xaa 7 -Cys-Xaa 8  (SEQ ID NO:2), as defined herein; or having the general formula III: Xaa 1 -Cys-Xaa 2 -Cys-Xaa 3 -Xaa 4 -Xaa 5 -Cys-Cys-Ser-Asn-Ser-Cys-Asp-Xaa 2 -Cys-Xaa 7  (SEQ ID NO:3), as described herein; or having the general formula IV: Xaa 1 -Cys-Xaa 2 -Cys-Xaa 3 -Xaa 4 -Xaa 5 -Cys-Cys-Ser-Asn-Ser-Cys-Asp-Xaa 6 -Cys-Xaa 7  (SEQ ID NO:4), as described herein; or having the general formula V: Xaa 1 -Xaa 2 -Cys-Xaa 3 -Xaa 4 -Phe-Xaa 5 -Cys-Thr-Xaa 6 -Ser-Xaa 7 -Cys-Cys-Ser-Asn-Ser-Cys-Asp-Gln-Thr-Tyr-Cys-Xaa 8 -Leu-Xaa 9  (SEQ ID NO:5), as described herein. The invention further relates to specific γ-conopeptides, specific pro-γ-conopeptides and nucleic acids encoding the pro-γ-conopeptides. The invention also includes pharmaceutically acceptable salts of the conopeptides. These conopeptides are useful as agonists of neuronal pacemaker calcium channels.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims benefit to U.S. provisional patent application Serial No. 60/069,706, filed Dec. 16, 1997, incorporated herein by reference.

This invention was made in part with Government support under Grant No. RR01614 and GM48677 awarded by the National Institutes of Health, Bethesda, Md. and under Grant No. DIR8700766 awarded by the National Science Foundation, Washington, D.C. The United States Government has certain rights in the invention.

BACKGROUND OF THE INVENTION

This invention relates to relatively short peptides about 25-40 residues in length, which are naturally available in minute amounts in the venom of the cone snails or analogs to the naturally available peptides, and which include three cyclizing disulfide linkages and one or more γ-carboxyglutamate residues.

The publications and other materials used herein to illuminate the background of the invention, and in particular, cases to provide additional details respecting the practice, are incorporated by reference, and for convenience are referenced in the following text by author and date and are listed alphabetically by author in the appended bibliography.

Mollusks of the genus Conus produce a venom that enables them to carry out their unique predatory lifestyle. Prey are immobilized by the venom that is injected by means of a highly specialized venom apparatus, a disposable hollow tooth that functions both in the manner of a harpoon and a hypodermic needle.

Few interactions between organisms are more striking than those between a venomous animal and its envenomated victim. Venom may be used as a primary weapon to capture prey or as a defense mechanism. Many of these venoms contain molecules directed to receptors and ion channels of neuromuscular systems.

The predatory cone snails (Conus) have developed a unique biological strategy. Their venom contains relatively small peptides that are targeted to various neuromuscular receptors and may be equivalent in their pharmacological diversity to the alkaloids of plants or secondary metabolites of microorganisms. Many of these peptides are among the smallest nucleic acid-encoded translation products having defined conformations, and as such, they are somewhat unusual. Peptides in this size range normally equilibrate among many conformations. Proteins having a fixed conformation are generally much larger.

The cone snails that produce these toxic peptides, which are generally referred to as conotoxins or conotoxin peptides, are a large genus of venomous gastropods comprising approximately 500 species. All cone snail species are predators that inject venom to capture prey, and the spectrum of animals that the genus as a whole can envenomate is broad. A wide variety of hunting strategies are used, however, every Conus species uses fundamentally the same basic pattern of envenomation.

Several peptides isolated from Conus venoms have been characterized. These include the α-, μ- and ω-conotoxins which target nicotinic acetylcholine receptors, muscle sodium channels, and neuronal calcium channels, respectively (Olivera et al., 1985). A conotoxin, TxVIIA, containing a γ-carboxyglutamate residue and three disulfide bonds has been isolated (Fainzilber et al., 1991). Conopressins, which are vasopressin analogs, have also been identified (Cruz et al., 1987). In addition, peptides named conantokins have been isolated from Conus geographus and Conus tulipa (Mena et al., 1990; Haack et al., 1990). These peptides have unusual age-dependent physiological effects: they induce a sleep-like state in mice younger than two weeks and hyperactive behavior in mice older than 3 weeks (Haack et al., 1990). Recently, peptides named contryphans containing D-tryptophan or D-leucine residues have been isolated from Conus radiatus (U.S. Ser. No. 09/061,026), and bromo-tryptophan conopeptides have been isolated from Conus imperialis and Conus radiatus (U.S. Ser. No. 08/785,534).

Ion channels are integral plasma membrane proteins responsible for electrical activity in excitable tissues. It has been recognized that slow inward currents can influence neuronal excitability via long-lasting depolarizations of the cell membrane (Llinás, 1988). The role of slow inward currents in generating endogenous bursting behavior has been recognized in molluscan neurons (Wilson & Wachtel, 1974; Eckert & Lux, 1976; Partridge et al., 1979), and more recently in some types of mammalian neurons (Lanthorn et al., 1984; Stafstrom et al., 1985; Llinàs, 1988; Alonso & Llinàs, 1989). Changes in the slow inward currents carried by such nonspecific cation channels may play a crucial role in bursting and pacemaker activities in a variety of excitable systems, ranging from mammalian heart muscle to molluscan neurons (Partridge & Swandulla, 1988; Hoehn et al., 1993; Kits & Mansvelder, 1966; van Soest & Kits, 1997). Slow inward currents are also believed to be important in generating epileptiform bursting in regions of the brain such as the hippocampus.

It is desired to identify drugs which are useful for modulating slow inward cation channels in vertebrates involved in syndromes of clinical relevance, such as epileptic activity in hippocampus (Hoehn et al., 1993) and pacemaker potentials in heart muscle (Reuter, 1984).

SUMMARY OF THE INVENTION

This invention relates to relatively short peptides about 25-40 residues in length, which are naturally available in minute amounts in the venom of the cone snails or analogs to the naturally available peptides, and which include three cyclizing disulfide linkages and one or more γ-carboxyglutamate residues.

More specifically, the present invention is directed to conopeptides having the general formula I:

Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Cys-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₃-Cys-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₄-Cys-Cys-Xaa₅-Xaa₆-Xaa₇-Xaa₈-Cys-Xaa₂-Xaa₂-Xaa_(2-Xaa) ₃-Xaa₃-Xaa₃-Cys-Xaa₉-Xaa₉-Xaa₁₀-Xaa₁₀-Xaa₁₀-Xaa₁₀-Xaa₁₀-Xaa₁₀-Xaa₁₀ (SEQ ID NO: 1), wherein Xaa₁ is des-Xaa₁ or any amino acid; Xaa₂ is any amino acid; Xaa₃ is des-Xaa₃ or any amino acid; Xaa₄ is Glu γ-Glu (γ-carboxyglutamic acid; also referred to as Gla) or Gln; Xaa₅ is any amino acid; Xaa₆ is any amino acid; Xaa₇ is any amino acid; Xaa₈ is des-Xaa₈ or any amino acid; Xaa₉ is des-Xaa₉ or any amino acid; and Xaa₁₀ is des-Xaa₁₀ or any amino acid, with the provisos that (a) when all Xaa₁₀ are des-Xaa₁₀, then both Xaa₉ are des-Xaa₉ or any amino acid and (b) when all Xaa₁ are des-Xaa₁, then Xaa₅-Xaa₆-Xaa₇-Xaa₈- is not Ser-Asp-Asn.

general formula II:

Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Cys-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₃-Cys-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₄-Cys-Cys-Xaa₅-Xaa₆-Xaa₇-Xaa₈-Cys-Xaa₂-Xaa₂-Xaa₂-Xaa₃-Xaa₃-Xaa₃-Cys-Xaa₉-Xaa₉-Xaa₁₀-Xaa₁₀-Xaa₁₀-Xaa₁₀-Xaa₁₀-Xaa₁₀-Xaa₁₀ (SEQ ID NO:2), wherein Xaa₁ is des-Xaa₁ or any amino acid; Xaa₂ is any amino acid; Xaa₃ is des-Xaa₃ or any amino acid; Xaa₄ is Glu, γ-Glu or Gln; Xaa₅ is Ser or Thr; Xaa₆ is any amino acid; Xaa₇ is any amino acid; Xaa₈ is des-Xaa₈ or any amino acid; Xaa₉ is des-Xaa₉ or any amino acid; and Xaa₁₀ is des-Xaa₁₀ or any amino acid, with the provisos that (a) when all Xaa₁₀ are des-Xaa₁₀, then both Xaa₉are des-Xaa₉ or any amino acid and (b) when all Xaa₁ are des-Xaa₁ and Xaa₅ is Ser, then Xaa₆-Xaa₇-Xaa₈- is not Asp-Asn.

general formula III:

Xaa₁-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Cys-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Cys-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₃-Cys-Cys-Ser-Asn-Ser-Cys-Asp-Xaa₁-Xaa₁-Xaa₁-Cys-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₂-Xaa₂ (SEQ ID NO:3), wherein Xaa₁ is any amino acid; Xaa₂ is des-Xaa₂ or any amino acid and Xaa₃ is Glu or γ-Glu.

general formula IV:

Xaa₁-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Xaa₂-Cys-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Cys-Xaa₃-Xaa₁-Xaa₁-Xaa₁-Xaa₄-Cys-Cys-Ser-Asn-Ser-Cys-Asp-Xaa₁-Xaa₁-Xaa₁-Cys-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₁-Xaa₂-Xaa₂ (SEQ ID NO:4), wherein Xaa₁ is any amino acid; Xaa₂ is des-Xaa₂ or any amino acid; Xaa₃ is Ser or Thr; and Xaa₄ is Glu or γ-Glu.

or general formula V:

Xaa₁-Xaa₁-Xaa₂-Cys-Xaa₃-Xaa₃-Xaa₄-Phe-Xaa₃-Xaa₃-Cys-Thr-Xaa₃-Xaa₃-Ser-Xaa₅-Cys-Cys-Ser-Asn-Ser-Cys-Asp-Gln-Thr-Tyr-Cys-Xaa₃-Leu-Xaa₃-Xaa₃-Xaa₃-Xaa₃-Xaa₃ (SEQ ID NO:5), wherein Xaa₁ is des-Xaa₁ or any amino acid; Xaa₂ is Asp, Glu or γ-Glu; Xaa₃ is any amino acid; Xaa₄ is Trp or 6-bromo-Trp; and Xaa₅ is Glu or γ-Glu.

The amino acid or the amino acid residues of the peptides is an amino acid selected from the group consisting of natural, modified or non-natural amino acids. The disulfide bridges in the conopeptides of general formulas I-V (as well as the specific conopeptides described herein) are between the first and fourth cysteine residues, between the second and fifth cysteine residues and between the third and sixth cysteine residues. The C-terminal end may contain a carboxyl or amide group. The invention also includes pharmaceutically acceptable salts of the conopeptides. These conopeptides are useful for modulating slow inward cation channels in vertebrates involved in syndromes of clinical relevance, such as epileptic activity in hippocampus (Hoehn et al., 1993) and pacemaker potentials in heart muscle (Reuter, 1984). Thus, the conopeptides are useful as agonists of neuronal pacemaker cation channels.

The invention further relates to the specific peptides:

Asp-Cys-Thr-Ser-Xaa₁-Phe-Gly-Arg-Cys-Thr-Val-Asn-Ser-Xaa₂-Cys-Cys-Ser-Asn-Ser-Cys-Asp-Gln-Thr-Tyr-Cys-Xaa₂-Leu-Tyr-Ala-Phe-Xaa₃-Ser (SEQ ID NO:6) (PnVIIA), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; Xaa₃ is Pro or hydroxy-Pro (Hyp), preferably Hyp; and the C-terminus is a free carboxyl group or is amidated, preferably a free carboxyl group;

Xaa₁-Leu-Xaa₂-Cys-Ser-Val-Xaa₁-Phe-Ser-His-Cys-Thr-Lys-Asp-Ser-Xaa₂-Cys-Cys-Ser-Asn-Ser-Cys-Asp-Gln-Thr-Tyr-Cys-Thr-Leu-Met-Xaa₃-Xaa₃-Asp-Xaa₁ (SEQ ID NO:7) (Tx6.4), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; Xaa₃ is Pro or Hyp, preferably Hyp; and the C-terminus is a free carboxyl group or is amidated, preferably a free carboxyl group;

Xaa₁-Xaa₁-Arg-Xaa₁-Gly-Gly-Cys-Met-Ala-Xaa₁-Phe-Gly-Leu-Cys-Ser-Arg-Asp-Ser-Xaa₂-Cys-Cys-Ser-Asn-Ser-Cys-Asp-Val-Thr-Arg-Cys-Xaa₂-Leu-Met-Xaa₃-Phe-Xaa₃-Xaa₃-Asp-Xaa₁ (SEQ ID NO:8) (Tx6.9), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; Xaa₃ is Pro or Hyp, preferably Hyp; and the C-terminus is a free carboxyl group or is amidated, preferably a free carboxyl group;

Cys-Lys-Thr-Tyr-Ser-Lys-Tyr-Cys-Xaa₂-Ala-Asp-Ser-Xaa₂-Cys-Cys-Thr-Xaa₂-Gln-Cys-Val-Arg-Ser-Tyr-Cys-Thr-Leu-Phe (SEQ ID NO:9) (J010), wherein Xaa₂ is Glu or γ-Glu, preferably γ-Glu; and the C-terminus is a free carboxyl group or is amidated, preferably amidated;

Asp-Xaa₁-Xaa₁-Asp-Asp-Gly-Cys-Ser-Val-Xaa₁-Gly-Xaa₃-Cys-Thr-Val-Asn-Ala-Xaa₂-Cys-Cys-Ser-Gly-Asp-Cys-His-Xaa₂-Thr-Cys-Ile-Phe-Gly-Xaa,-Xaa₂-Val (SEQ ID NO:10) (Tx6.6), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; Xaa₃ is Pro or Hyp, preferably Hyp; and the C-terminus is a free carboxyl group or is amidated, preferably a free carboxyl group;

Gly-Met-Xaa₁-Gly-Xaa₂-Cys-Lys-Asp-Gly-Leu-Thr-Thr-Cys-Leu-Ala-Xaa₃-Ser-Xaa₂-Cys-Cys-Ser-Xaa₂-Asp-Cys-Xaa₂-Gly-Ser-Cys-Thr-Met-Xaa₁(SEQ ID NO:11) (Tx6.5), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; Xaa₃ is Pro or Hyp, preferably Hyp; and the C-terminus is a free carboxyl group or is amidated, preferably a free carboxyl group;

Xaa₂-Cys-Arg-Ala-Xaa₁-Tyr-Ala-Xaa₃-Cys-Ser-Xaa₃-Gly-Ala-Gln-Cys-Cys-Ser-Leu-Leu-Met-Cys-Ser-Lys-Ala-Thr-Ser-Arg-Cys-Ile-Leu-Ala-Leu (SEQ ID NO:12) (Gm6.7), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; Xaa₃ is Pro or Hyp, preferably Hyp; and the C-terminus is a free carboxyl group or is amidated, preferably a free carboxyl group;

Asn-Gly-Gln-Cys-Xaa₂-Asp-Val-Xaa₁-Met-Xaa₃-Cys-Thr-Ser-Asn-Xaa₁-Xaa₂-Cys-Cys-Ser-Leu-Asp-Cys-Xaa₂-Met-Tyr-Cys-Thr-Gln-Ile (SEQ ID NO:13) (Mr6.1), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; Xaa₃ is Pro or Hyp, preferably Hyp; and the C-terminus is a free carboxyl group or is amidated, preferably amidated;

Cys-Gly-Gly-Xaa₁-Ser-Thr-Tyr-Cys-Xaa₂-Val-Asp-Xaa₂-Xaa₂-Cys-Cys-Ser-Xaa₂-Ser-Cys-Val-Arg-Ser-Tyr-Cys-Thr-Leu-Phe (SEQ ID NO:14) (Mr6.2), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; and the C-terminus is a free carboxyl group or is amidated, preferably amidated;

Asn-Gly-Gly-Cys-Lys-Ala-Thr-Xaa₁-Met-Ser-Cys-Ser-Ser-Gly-Xaa₁-Xaa₂-Cys-Cys-Ser-Met-Ser-Cys-Asp-Met-Try-Cys (SEQ ID NO:15) (Mr6.3), wherein Xaa₁ is Trp or 6-bromo-Trp; Xaa₂ is Glu or γ-Glu, preferably γ-Glu; and the C-terminus is a free carboxyl group or is amidated, preferably amidated.

Finally, the invention further relates to the propeptide sequences for the above peptides and the DNA sequences coding for these propeptide sequences as described in further detail herein.

SEQUENCE SUMMARY

SEQ ID NO:1=γ-conopeptides of general formula I; SEQ ID NO:2=γ-conopeptides of general formula II; SEQ ID NO:3=γ-conopeptides of general formula III; SEQ ID NO:4=γ-conopeptides of general formula IV; SEQ ID NO:5=γ-conopeptides of general formula V; SEQ ID NO:6=γ-conopeptide corresponding to PnVIIA; SEQ ID NO:7=γ-conopeptide corresponding to Tx6.4; SEQ ID NO:8=γ-conopeptide corresponding to Tx6.9; SEQ ID NO:9=γ-conopeptide corresponding to J010; SEQ ID NO:10=γ-conopeptide corresponding to Tx6.6; SEQ ID NO:11=γ-conopeptide corresponding to Tx6.5; SEQ ID NO:12=γ-conopeptide corresponding to Gm6.7; SEQ ID NO:13=γ-conopeptide corresponding to Mr6.1; SEQ ID NO:14=γ-conopeptide corresponding to Mr6.2; SEQ ID NO:15=γ-conopeptide corresponding to Mr6.3; SEQ ID NO:16=DNA encoding propeptide of Tx6.4; SEQ ID NO:17=propeptide of Tx6.4; SEQ ID NO:18=DNA encoding propeptide of Tx6.9; SEQ ID NO:19=propeptide of Tx6.9; SEQ ID NO:20=DNA encoding propeptide of J010; SEQ ID NO:21=propeptide of J010; SEQ ID NO:22=DNA encoding propeptide of Tx6.6; SEQ ID NO:23=propeptide of Tx6.6; SEQ ID NO:24=DNA encoding propeptide of Tx6.5; SEQ ID NO:25=propeptide of Tx6.5; SEQ ID NO:26=DNA encoding propeptide of Gm6.7; SEQ ID NO:27=propeptide of Gm6.7; SEQ ID NO:28=DNA encoding propeptide of Mr6. 1; SEQ ID NO:29=propeptide of Mr6.1; SEQ ID NO:30=DNA encoding propeptide of Mr6.2; SEQ ID NO:31=propeptide of Mr6.2; SEQ ID NO:32=DNA encoding propeptide of Mr6.3; SEQ ID NO:33=propeptide of Mr6.3; SEQ ID NO:34=DNA encoding propeptide of Tx6.1; SEQ ID NO:35=propeptide of Tx6.1; SEQ ID NO:36=γ-conopeptide corresponding to Tx6.1; SEQ ID NO:37=consensus sequence of γ-conopeptides PnVIIA and Tx6.4; SEQ ID NO:38=degenerate probe for consensus sequence of γ-conopeptides; SEQ ID NO:39=degenerate probe for consensus sequence of γ-conopeptides; SEQ ID NO:40=consensus sequence of pro-γ-conopeptides; SEQ ID NO:41=degenerate probe for consensus sequence of pro-γ-conopeptides; SEQ ID NO:42=γ-conopeptide PnVIIA; SEQ ID NO:43=γ-conopeptide TxVIIA; SEQ ID NO:44=N-terminal tryptic peptide of γ-conopeptide PnVIIA; SEQ ID NO:45=C-terminal tryptic peptide of γ-conopeptide PnVIIA; SEQ ID NO:46=primer for isolating conopeptides from Conus textile cDNA library; SEQ ID NO:47=primer for isolating conopeptides from Conus textile cDNA library.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This invention relates to relatively short peptides about 25-40 residues in length, which are naturally available in minute amounts in the venom of the cone snails or analogs to the naturally available peptides, and which include three cyclizing disulfide linkages and one or more γ-carboxyglutamate residues.

More specifically, the present invention is directed to conopeptides having the general formulas I-V described above. The invention is also directed to the specific γ-conopeptides PnVIIA, Tx6.4, Tx6.9, J010, Tx6.6, Tx6.5, Gm6.7, Mr6.1, Mr6.2 and Mr6.3, the sequences of which are described above.

The invention is further directed to isolated nucleic acids which encode γ-conopeptides, including the above and γ-conopeptide Tx6.1, and to isolated propeptides encoded by the nucleic acids. This aspect of the present invention is set forth in Table 1.

TABLE 1 Nucleic Acids and Propeptides of γ-Conopeptides γ-Conopeptide Nucleic Acid SEQ ID NO: Propeptide SEQ ID NO: Tx6.4 16 17 Tx6.9 18 19 J010 20 21 Tx6.6 22 23 Tx6.5 24 25 Gm6.7 26 27 Mr6.1 28 29 Mr6.2 30 31 Mr6.3 32 33 Tx6.1 34 35 The mature peptide sequence for Tx6.1 is LCX₃DYTX₂X₃CSHAHX₂CCSX₁NCYNGHCT (SEQ ID NO:36), wherein X₁, X₂ and X₃ are as described for Xaa ,₁Xaa ₂and Xaa, ₃ respectively. The C-terminus is preferably amidated.

The conopeptides of the present invention are useful for modulating slow inward cation channels in vertebrates involved in syndromes of clinical relevance, such as epileptic activity in hippocampus (Hoehn et al., 1993) and pacemaker potentials in heart muscle (Reuter, 1984). Thus, the conopeptides are useful as agonists of neuronal pacemaker cation channels.

The γ-conopeptides of the present invention are identified by isolation from Conus venom. Alternatively, the γ-conopeptides of the present invention are identified using recombinant DNA techniques. According to this method of identification, cDNA libraries of various Conus species are screened using conventional techniques with degenerate probes for the peptide consensus sequence Xaa-Cys-Cys-Ser (SEQ ID NO:37), wherein Xaa is Glu or Gln. Suitable probes are 5′ SARTGYTGYAGY 3′ (SEQ ID NO:38) or 5′ SARTGYTGYTCN 3′ (SEQ ID NO:39). Alternatively, cDNA libraries are screened with degenerate probes for the propeptide consensus sequence Ile-Leu-Leu-Val-Ala-Ala-Val-Leu (SEQ ID NO:40). Suitable probes for this sequence are 5′ ATHYTNYTNGTNGCNGCNGTNYTN 3′ (SEQ ID NO:4 1). Clones which hybridize to these probes are analyzed to identify those which meet minimal size requirements, i.e., clones having approximately 300 nucleotides (for a propeptide), as determined using PCR primers which flank the cDNA cloning sites for the specific cDNA library being examined. These minimal-sized clones are then sequenced. The sequences are then examined for the presence of a peptide having the characteristics noted above for γ-conopeptides, such as the presence of a Glu residue which could be modified to a γ-Glu and 6 cysteine residues. The biological activity of the peptides identified by this method is tested as described herein.

These peptides are sufficiently small to be chemically synthesized. General chemical syntheses for preparing the foregoing conopeptides peptides are described hereinafter, along with specific chemical synthesis of conopeptides and indications of biological activities of these synthetic products. Various ones of these conopeptides can also be obtained by isolation and purification from specific Conus species using the techniques described in U.S. Pat. No. 4,447,356 (Olivera et al., 1984), U.S. Pat. No. 5,514,774 (Olivera et al., 1996) and U.S. Pat. No. 5,591,821 (Olivera et al., 1997), the disclosures of which are incorporated herein by reference.

Although the conopeptides of the present invention can be obtained by purification from cone snails, because the amounts of conopeptides obtainable from individual snails are very small, the desired substantially pure conopeptides are best practically obtained in commercially valuable amounts by chemical synthesis using solid-phase strategy. For example, the yield from a single cone snail may be about 10 micrograms or less of conopeptide. By “substantially pure” is meant that the peptide is present in the substantial absence of other biological molecules of the same type; it is preferably present in an amount of at least about 85% purity and preferably at least about 95% purity. Chemical synthesis of biologically active conopeptides depends of course upon correct determination of the amino acid sequence. Thus, the conopeptides of the present invention may be isolated, synthesized and/or substantially pure.

The conopeptides can also be produced by recombinant DNA techniques well known in the art. Such techniques are described by Sambrook et al. (1979). The peptides produced in this manner are isolated, reduced if necessary, and oxidized to form the correct disulfide bonds, if present in the final molecule.

One method of forming disulfide bonds in the conopeptides of the present invention is the air oxidation of the linear peptides for prolonged periods under cold room temperatures or at room temperature. This procedure results in the creation of a substantial amount of the bioactive, disulfide-linked peptides. The oxidized peptides are fractionated using reverse-phase high performance liquid chromatography (HPLC) or the like, to separate peptides having different linked configurations. Thereafter, either by comparing these fractions with the elution of the native material or by using a simple assay, the particular fraction having the correct linkage for maximum biological potency is easily determined. It is also found that the linear peptide, or the oxidized product having more than one fraction, can sometimes be used for in vivo administration because the cross-linking and/or rearrangement which occurs in vivo has been found to create the biologically potent conopeptide molecule. However, because of the dilution resulting from the presence of other fractions of less biopotency, a somewhat higher dosage may be required.

The peptides are synthesized by a suitable method, such as by exclusively solid-phase techniques, by partial solid-phase techniques, by fragment condensation or by classical solution couplings.

In conventional solution phase peptide synthesis, the peptide chain can be prepared by a series of coupling reactions in which constituent amino acids are added to the growing peptide chain in the desired sequence. Use of various coupling reagents, e.g., dicyclohexylcarbodiimide or diisopropylcarbonyldimidazole, various active esters, e.g., esters of N-hydroxyphthalimide or N-hydroxy-succinimide, and the various cleavage reagents, to carry out reaction in solution, with subsequent isolation and purification of intermediates, is well known classical peptide methodology. Classical solution synthesis is described in detail in the treatise, “Methoden der Organischen Chemie (Houben-Weyl): Synthese von Peptiden,” (1974). Techniques of exclusively solid-phase synthesis are set forth in the textbook, “Solid-Phase Peptide Synthesis,” (Stewart and Young, 1969), and are exemplified by the disclosure of U.S. Pat. No. 4,105,603 (Vale et al., 1978). The fragment condensation method of synthesis is exemplified in U.S. Pat. No. 3,972,859 (1976). Other available syntheses are exemplified by U.S. Pat. No. 3,842,067 (1974) and U.S. Pat. No. 3,862,925 (1975). The synthesis of peptides containing γ-carboxyglutamic acid residues is exemplified by Rivier et al. 29 (1987), Nishiuchi et al. (1993) and Zhou et al. (1996). Synthesis of conopeptides have been described in U.S. Pat. No. 4,447,356 (Olivera et al., 1984), U.S. Pat. No. 5,514,774 (Olivera et al., 1996) and U.S. Pat. No. 5,591,821 (Olivera et al., 1997).

Common to such chemical syntheses is the protection of the labile side chain groups of the various amino acid moieties with suitable protecting groups which will prevent a chemical reaction from occurring at that site until the group is ultimately removed. Usually also common is the protection of an α-amino group on an amino acid or a fragment while that entity reacts at the carboxyl group, followed by the selective removal of the α-amino protecting group to allow subsequent reaction to take place at that location. Accordingly, it is common that, as a step in such a synthesis, an intermediate compound is produced which includes each of the amino acid residues located in its desired sequence in the peptide chain with appropriate side-chain protecting groups linked to various ones of the residues having labile side chains.

As far as the selection of a side chain amino protecting group is concerned, generally one is chosen which is not removed during deprotection of the α-amino groups during the synthesis. However, for some amino acids, e.g., His, protection is not generally necessary. In selecting a particular side chain protecting group to be used in the synthesis of the peptides, the following general rules are followed: (a) the protecting group preferably retains its protecting properties and is not split off under coupling conditions, (b) the protecting group should be stable under the reaction conditions selected for removing the α-amino protecting group at each step of the synthesis, and (c) the side chain protecting group must be removable, upon the completion of the synthesis containing the desired amino acid sequence, under reaction conditions that will not undesirably alter the peptide chain.

It should be possible to prepare many, or even all, of these peptides using recombinant DNA technology. However, when peptides are not so prepared, they are preferably prepared using the Merrifield solid-phase synthesis, although other equivalent chemical syntheses known in the art can also be used as previously mentioned. Solid-phase synthesis is commenced from the C-terminus of the peptide by coupling a protected α-amino acid to a suitable resin. Such a starting material can be prepared by attaching an α-amino-protected amino acid by an ester linkage to a chloromethylated resin or a hydroxymethyl resin, or by an amide bond to a benzhydrylamine (BHA) resin or paramethylbenzhydrylamine (MBHA) resin. Preparation of the hydroxymethyl resin is described by Bodansky et al. (1966). Chloromethylated resins are commercially available from Bio Rad Laboratories (Richmond, Calif.) and from Lab. Systems, Inc. The preparation of such a resin is described by Stewart and Young (1969). BHA and MBHA resin supports are commercially available, and are generally used when the desired polypeptide being synthesized has an unsubstituted amide at the C-terminus. Thus, solid resin supports may be any of those known in the art, such as one having the formulae —O—CH₂-resin support, —NH BHA resin support, or —NH-MBHA resin support. When the unsubstituted amide is desired, use of a BHA or MBHA resin is preferred, because cleavage directly gives the amide. In case the N-methyl amide is desired, it can be generated from an N-methyl BHA resin. Should other substituted amides be desired, the teaching of U.S. Pat. No. 4,569,967 (Kornreich et al., 1986) can be used, or should still other groups than the free acid be desired at the C-terminus, it may be preferable to synthesize the peptide using classical methods as set forth in the Houben-Weyl text (1974).

The C-terminal amino acid, protected by Boc or Fmoc and by a side-chain protecting group, if appropriate, can be first coupled to a chloromethylated resin according to the procedure set forth in Horiki et al. (1978), using KF in DMF at about 60° C. for 24 hours with stirring, when a peptide having free acid at the C-terminus is to be synthesized. Following the coupling of the BOC-protected amino acid to the resin support, the α-amino protecting group is removed, as by using trifluoroacetic acid (TFA) in methylene chloride or TFA alone. The deprotection is carried out at a temperature between about 0° C. and room temperature. Other standard cleaving reagents, such as HCl in dioxane, and conditions for removal of specific α-amino protecting groups may be used as described in Schroder and Lubke (1965).

After removal of the α-amino-protecting group, the remaining α-amino- and side chain-protected amino acids are coupled step-wise in the desired order to obtain the intermediate compound defined hereinbefore, or as an alternative to adding each amino acid separately in the synthesis, some of them may be coupled to one another prior to addition to the solid phase reactor. Selection of an appropriate coupling reagent is within the skill of the art. Particularly suitable as a coupling reagent is N,N′-dicyclohexylcarbodiimide (DCC, DIC, HBTU, HATU, TBTU in the presence of HoBt or HoAt).

The activating reagents used in the solid phase synthesis of the peptides are well known in the peptide art. Examples of suitable activating reagents are carbodiimides, such as N,N′-diisopropylcarbodiimide and N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide. Other activating reagents and their use in peptide coupling are described by Schroder and Lubke (1965) and Kapoor (1970).

Each protected amino acid or amino acid sequence is introduced into the solid-phase reactor in about a twofold or more excess, and the coupling may be carried out in a medium of dimethylformamide (DMF):CH₂Cl₂ (1:1) or in DMF or CH₂Cl, alone. In cases where intermediate coupling occurs, the coupling procedure is repeated before removal of the α-amino protecting group prior to the coupling of the next amino acid. The success of the coupling reaction at each stage of the synthesis, if performed manually, is preferably monitored by the ninhydrin reaction, as described by Kaiser et al. (1970). Coupling reactions can be performed automatically, as on a Beckman 990 automatic synthesizer, using a program such as that reported in Rivier et al. (1978).

After the desired amino acid sequence has been completed, the intermediate peptide can be removed from the resin support by treatment with a reagent, such as liquid hydrogen fluoride or TFA (if using Fmoc chemistry), which not only cleaves the peptide from the resin but also cleaves all remaining side chain protecting groups and also the α-amino protecting group at the N-terminus if it was not previously removed to obtain the peptide in the form of the free acid. If Met is present in the sequence, the Boc protecting group is preferably first removed using trifluoroacetic acid (TFA)/ethanedithiol prior to cleaving the peptide from the resin with HF to eliminate potential S-alkylation. When using hydrogen fluoride or TFA for cleaving, one or more scavengers such as anisole, cresol, dimethyl sulfide and methylethyl sulfide are included in the reaction vessel.

Cyclization of the linear peptide is preferably affected, as opposed to cyclizing the peptide while a part of the peptido-resin, to create bonds between Cys residues. To effect such a disulfide cyclizing linkage, fully protected peptide can be cleaved from a hydroxymethylated resin or a chloromethylated resin support by ammonolysis, as is well known in the art, to yield the fully protected amide intermediate, which is thereafter suitably cyclized and deprotected. Alternatively, deprotection, as well as cleavage of the peptide from the above resins or a benzhydrylamine (BHA) resin or a methylbenzhydrylamine (MBHA), can take place at 0° C. with hydrofluoric acid (HF) or TFA, followed by oxidation as described above. A suitable method for cyclization is the method described by Cartier et al. (1996).

The present γ-conotoxins are useful for modulating slow inward cation channels in 1:57, vertebrates involved in syndromes of clinical relevance, such as epileptic activity in hippocampus (Hoehn et al., 1993) and pacemaker potentials in heart muscle (Reuter, 1984). Thus, the conopeptides are useful as agonists of neuronal pacemaker cation channels.

Pharmaceutical compositions containing a compound of the present invention as the active ingredient can be prepared according to conventional pharmaceutical compounding techniques. See, for example, Remington's Pharmaceutical Sciences, 18th Ed. (1990, Mack Publishing Co., Easton, Pa.). Typically, an antagonistic amount of active ingredient will be admixed with a pharmaceutically acceptable carrier. The carrier may take a wide variety of forms depending on the form of preparation desired for administration, e.g., intravenous, oral or parenteral. The compositions may further contain antioxidizing agents, stabilizing agents, preservatives and the like.

For oral administration, the compounds can be formulated into solid or liquid preparations such as capsules, pills, tablets, lozenges, melts, powders, suspensions or emulsions. In preparing the compositions in oral dosage form, any of the usual pharmaceutical media may be employed, such as, for example, water, glycols, oils, alcohols, flavoring agents, preservatives, coloring agents, suspending agents, and the like in the case of oral liquid preparations (such as, for example, suspensions, elixirs and solutions); or carriers such as starches, sugars, diluents, granulating agents, lubricants, binders, disintegrating agents and the like in the case of oral solid preparations (such as, for example, powders, capsules and tablets). Because of their ease in administration, tablets and capsules represent the most advantageous oral dosage unit form, in which case solid pharmaceutical carriers are obviously employed. If desired, tablets may be sugar-coated or enteric-coated by standard techniques. The active agent can be encapsulated to make it stable to passage through the gastrointestinal tract while at the same time allowing for passage across the blood brain barrier. See for example, WO 96/11698.

For parenteral administration, the compound may dissolved in a pharmaceutical carrier and administered as either a solution of a suspension. Illustrative of suitable carriers are water, saline, dextrose solutions, fructose solutions, ethanol, or oils of animal, vegetative or synthetic origin. The carrier may also contain other ingredients, for example, preservatives, suspending agents, solubilizing agents, buffers and the like. When the compounds are being administered intrathecally, they may also be dissolved in cerebrospinal fluid.

The conopeptides are administered in an amount sufficient to agonize the neuronal pacemaker calcium channels. The dosage range at which the conopeptides exhibit this agonistic effect can vary widely depending upon the particular condition being treated, the severity of the patient's condition, the patient, the specific conopeptide being administered, the route of administration and the presence of other underlying disease states within the patient. Typically, the conopeptides of the present invention exhibit their therapeutic effect at a dosage range from about 0.05 mg/kg to about 250 mg/kg, and preferably from about 0.1 mg/kg to about 100 mg/kg of the active ingredient. A suitable dose can be administered in multiple sub-doses per day. Typically, a dose or sub-dose may contain from about 0.1 mg to about 500 mg of the active ingredient per unit dosage form. A more preferred dosage will contain from about 0.5 mg to about 100 mg of active ingredient per unit dosage form. Dosages are generally initiated at lower levels and increased until desired effects are achieved.

EXAMPLES

The present invention is described by reference to the following Examples, which are offered by way of illustration and are not intended to limit the invention in any manner. Standard techniques well known in the art or the techniques specifically described below were utilized.

Example 1 Experimental Procedures

Toxins and Bioassays. Venom of Conus pennaceus was obtained from specimens collected in the Northern Red Sea. Conotoxin-TxVIIA was from venom-purified aliquots (Fainzilber et al., 1991). Assays for paralysis in limpet snails (Patella caerulea), bivalves (Mytilus edulis), and fish (Gambusia affinis) were performed as previously described (Fainzilber et al., 1995).

Column Chromatography. Conus pennaceus venom was extracted and fractionated on Sephadex G-50 (Pharmacia) and semipreparative C18 (Vydac) columns as previously described (Fainzilber et al., 1994). Final purification of the active peptides was on wide pore reverse-phase phenyl (Vydac, 25×0.46 cm, 0.5 μm particle size) as described in FIG. 1, with on-line spectral analysis of peak purity utilizing a Hewlett-Packard 1040A Diode Array Detector coupled with HP 300 Chemstation Software.

Amino Acid Analysis. Analysis of amino acid composition after acid hydrolysis and 9-fluorenylmethyl-oxycabonyl-chloride (FMOC) derivatization was performed on a Merck-Hitachi reverse-phase HPLC system, according to Betner & Foldi, 1988. The system was calibrated prior to each analysis with FMOC-amino acid standards.

Reduction and alkylation. Dried purified peptides were dissolved in 50 μl of 0.1M NH₄HCO₃ (pH 8) containing 6M guanidine-HCl and 10 μM EDTA, and reduced with 200 μg of D11 at 37° C. for 2 hrs under argon. 4 vinylpyridine, or iodoacetic acid, or iodoacetamide were added and the mixture incubated at 37° C. for 1.5 hrs under argon. The alkylated peptide sample was purified on reverse-phase HPLC immediately after derivatization.

Edman Degradation Analyses. Reverse-phase purified peptides were applied to PVDF or glass fiber filters, and sequenced by automated Edman degradation on an Applied Biosystems 475A gas-phase protein sequencing system.

Proteolytic digest. HPLC purified sample of reduced and alkylated peptide was digested with TPCK-trypsin (Pierce, Rockford, Ill.) for 20 hrs at 37° C. A portion of the digest was directly analyzed by LCIESI/MS, and the remainder purified by reverse-phase HPLC. pH of the digest was adjusted to 3.0 prior to loading on the HPLC, in order to minimize the possibility of γ-carboxyglutamate decomposition in extremely acidic conditions. Purified C-terminal peptide fragments were further digested by Endoproteinase Asp-N (Boehringer-Mannheim, Indianapolis, Ind.) for 20 hrs at 37° C., and immediately purified on reverse-phase HPLC. A portion of the purified Asp N peptide was then methylated for LSI CID mass spectrometry.

Mass spectrometry. Microbore LC/ESI/MS experiments were carried out on a VG/Fisons (Manchester, U.K.) platform mass spectrometer using a C18 column (macrosphere C18, 5 μm particle size, 1×250 mm, Alitech, Deerfield Ill.) with a linear gradient of 2-62% acetonitrile in 0. 1% TFA in 60 min. A post column addition of make up solvent, 2-propanol/2-methoxyethanol (1:1) was used to optimize spraying and ionization performance (Medzihradszky et al., 1994). High energy CID mass spectra were obtained with a Kratos (Manchester, U.K.) Concept IIHH tandem mass spectrometer equipped with a continuous flow liquid secondary ionization source and a scanning charge-coupled device array detector (Burlingame, 1994).

Electrophysiology. Isolated Lymnaea caudodorsal neurons were kept in Petri dishes (Costar) and bathed in Hepes buffered saline (in mM: NaCl 30, NaCH₃SO₄10, NaHCO₃ 5, KCl 1.7, CaCl₂ 4, MgCl₂ 1.5, HEPES 10; pH 7.8 set with NaOH). To record calcium, sodium or potassium currents, HBS was replaced under continuous perfusion by the appropriate saline. The compositions of extracellular and pipette solutions used to selectively record specific currents were as follows (in 10 mM): Extracellular I_(Ca) saline: TEACl 40, CaCl₂ 4, HEPES 10, 4aminopyridine 2, pH 7.8 set with TEAOH; Extracellular I_(Na) saline: NaCl 47.5, CaCl₂ 4, MgCl₂ 1, HEPES 10, CdCl 0.1, 4-aminopyridine 1, pH 7.8 set with NaOH; Pipette saline (I_(Ca) and I_(Na)): CsCl 29, CaCl₂ 2.3, HEPES 10, EGTA 11, ATPMg 2, GTPtris 0.1, pH 7.4 adjusted with CsOH; Pipette saline (non-selective): KCl 29, CaCl₂ 2.3, HEPES 10, EGTA 11, ATPMg 2, GTPtris 0.1, pH 7.4 adjusted with KOH. Toxin was administered by means of a laboratory-built pressure ejection system through a small glass pipette (tip diameter 20 μM) placed at ˜100 μM from the recorded cell. This enabled rapid application of toxins, which were applied continuously during voltage ramps or series of depolarizing voltage steps.

Membrane potential measurements were performed using sharp microelectrodes filled with 0.5 M KCl (40 MΩ) using an Axoclamp 2A (Axon Instr., Foster City, Iowa) amplifier in the bridge balance mode. Whole-cell voltage-clamp experiments were performed using the Axoclamp 2A amplifier in the continuous single electrode voltage clamp mode. Pipettes (2-6 MΩ) were pulled on a Flaming/Brown P-87 (Sutter Instruments, CO) horizontal micro-electrode puller from Clark GC-150T glass (Clark Electromedical Instruments, U.K.) (seal resistance >1 GΩ). After disrupture of the patch membrane series resistance (<10 MΩ) was compensated for −80%. With current amplitudes of <5 nA, the maximal voltage error is estimated to be <10 mV. Cell capacitance (˜100 pF) was not compensated. Measurements of calcium or sodium currents were commenced 20 mins after access to the cell, in order to allow equilibration with the pipette solution. Data acquisition was controlled by a CED AD/DA converter (Cambridge Electronics Design, Cambridge, U.K.) 30 connected to an Intel 80486-based computer, run with voltage-clamp software developed in our laboratory. The current recordings were filtered at 1-5 kHz, sampled at 1 kHz (calcium currents and K+ currents) or 3 kHz (Na+ currents) and stored on-line. This system allowed simultaneous application of voltage-steps, acquisition of current recordings and timed application of toxins.

Example 2 Purification of γ-Conotoxin PnVIIA

Conus pennaceus venom was fractionated as described under Methods, and reverse-phase peptide containing fractions were assayed for γGlu content using a comparison of positive ion versus negative ion modes of MALDI mass spectrometry (Nakamura et al., 1996). The positive fraction indicated as PnVII in FIG. 1B of Fainzilber et al. (1994) was repurified by reverse phase phenyl chromatography and conotoxin-PnVIIA was obtained as the major component. On-line spectral analyses of the final chromatographic step suggested homogeneity of the purified toxin. ESI/MS measurements of the purified peptide revealed a single mass of 3718.4, further confirming homogeneity of PnVIIA.

Example 3 Chemical Characterization of γ-Conotoxin PnVIIA

Automated Edman sequencing of PnVIIA after alkylation with 4-vinylpyridine revealed a 32 amino acid sequence, allowing unambiguous assignments of 30 residues (Table 2). The extremely low yields of Glu at steps 14 and 26 further suggested the presence of γ-carboxyglutamate residues at these positions. Amino acid composition analysis (Table 3) was consistent with the proposed sequence (Table 4), and the ESI/MS measurement fits that predicted from the sequence assuming two γ-carboxyglutamate residues, three disulfide bridges and a free carboxy terminus (measured mass 3718.4, predicted 3719.0).

TABLE 2 Edman Degradation of PnVIIA Assigned Yield Cycle # Residue (pmoles) 1 Asp 185 2 Cys 170 3 Thr 180 4 Ser 190 5 Trp 170 6 Phe 140 7 Gly 210 8 Arg 85 9 Cys 93 10 Thr 150 11 Val 170 12 Asn 85 13 Ser 110 14 Glu 9 15 Cys 50 16 Cys 56 17 Ser 18 18 Asn 35 19 Ser 15 20 Cys 11 21 Asp 23 22 Gln 26 23 Thr 22 24 Tyr 17 25 Cys 14 26 Glu 3 27 Leu 17 28 Tyr 14 29 Ala 11 30 Phe 13 31 Hyp 8 32 Ser 9

TABLE 3 Amino Acid Composition Analysis of Conotoxin-PnVIIA Amino Acid Mole Ratio Asx 3.9 (4) Ser 4.7 (5) Glx 3.0 (3) Cys 5.2 (6) Thr 2.8 (3) Gly 1.1 (1) Arg 1.0 (1) Hyp 0.8 (1) Ala 1.2 (1) Tyr 2.0 (2) Val 1.2 (1) Phe 2.0 (2) Leu 1.2 (1) Trp n.d (1) Molar ratios of amino acids determined after acid hydrolysis and FMOC derivatization. Values in brackets are those predicted from the amino acid sequence.

TABLE 4 Amino Acid Sequence of PnVIIA and TxVIIA PnVIIA (SEQ ID NO: 42): D C TSWFGR C T V N SγCCS N S C DQT YC γ L YAFOS—COOH TxVIIA (SEQ ID NO: 43): C GGYSTY C γ V D SγCCS D N C VRS YC T L F—NH₂ Sequence identities are underlined; similarities are in bold type; and spaces inserted to maximize homologies.

In order to verify the presence of γcarboxyglutamate, and to determine the C-terminus, the peptide was further analyzed by mass spectrometry. A tryptic digest of reduced and carboxymethylated PnVIIA gave two peptides, T1 and T2, whose average molecular masses by ESI/MS were 1029.0 and 3062.6, respectively. These masses fit those predicted for the two PnVIIA tryptic peptides, namely 1029.1 for the sequence DXTSWFGR (SEQ ID NO:44), where X is carboxymethylCys, and 3062.2 for the sequence XTVNSX₁XXSNSXDQTYXX₁LYAFX₂S (SEQ ID NO:45), where X₁ is γ-carboxyglutamate and X₂ is 4-trans-hydroxyproline. Asp-N digest of the C-terminal tryptic peptide T2 gave two products, AN1 and AN2. ESI/MS average mass for AN1 was 1525.4, fitting the predicted mass of the Asp-N fragment XTVNSX₁XXSNSX (residues 1-12 of SEQ ID NO:45; predicted 1525.6). The monoisotopic LSI/MS measured mass for the C-terminal fragment AN2 was 1553.7, in agreement with the calculated value assuming the C-terminal is a free acid. An attempt to further confirm the C-terminal sequence of PnVIIA by LSI tandem MS failed, perhaps due to poor ionization efficiency of AN2. Therefore, PnVIIA was reduced and alkylated with iodoacetamide, a procedure expected to generate derivatives with better CID spectra than carboxymethylated peptides. After trypsin followed by Asp-N digests, the C-terminal carbamolmethylated peptide AN2u was isolated. Methylation with HCl/MeOH gave a tetra ester, with monoisotopic LSI/MS mass of 1608.9. This mass fits a peptide with incorporation of four methyl groups—one at the side chain of Asp, two at the carboxyl groups of the γ-carboxyglutamate, and the fourth at the presumed C-terminal free carboxyl (predicted monoisotopic mass 1608.7). The protonated tetra-methylated AN2u was further analyzed by CID mass spectrometry, giving a spectrum confining all details of the C-terminal sequence. The γ-carboxyglutamate residue is clearly indicated by the immonium ion at m/z 174, and its position revealed by the b5 and b6 molecular ions. The y2 ion confirms a C-terminal structure of —Hyp-Ser-OMe, derived from the free carboxy terminal of PnVIIA. Thus, the sequence of the peptide including the modified residues γ-carboxyglutamate and Hyp was confirmed; and the free carboxy terminus established by mass spectrometry.

PnVIIA belongs to the large group of conotoxins with the cysteine framework of ω and δ conotoxins, however, the sequence is most homologous to conotoxin-TxVIIA (Table 4). These homologies comprise approximately 48% amino acid identity and 63% similarity, including positioning of most hydrophobic and some charged residues, as well as one of the γ-carboxyglutamates.

Example 4 Biological Activity of γ-Conotoxin PnVIIA

Paralytic Activity of PnVIIA. Initial injections of PnVIIA to limpet snails (Patella) did not reveal the contractile paralysis previously observed for TxVIIA and other conotoxins in this bioassay (Fainzilber et al., 1991), however at doses above 50 pmoles/100 mg body weight some flaccidity of the foot musculature could be observed. Flaccid or relaxation paralytic effects are more easily observed in bioassays on bivalve molluscs, hence toxicity of PnVIIA was quantified in bioassays in freshwater mussels (Mytilus), as previously done for conotoxins PnIVA and PnIVB (Fainzilber et al., 1995). The ED₅₀ for Mytilus paralysis was 63.2 pmoles/100 mg body weight. No toxic or other effects could be observed upon injection of 1 nmole PnVEA (15-fold higher than the Mytilus ED₅₀) per 100 mg body weight in Gambusia fish or blowfly (Sarcophaga) larvae. Interestingly, decarboxylated PnVIIA had no observable effects on Mytilus at doses of up to five-fold the ED₅₀ of the native peptide.

Electrophysiological Effects of PnVIIA on Lymnaea Neuroendocrine Cells. Effects of PnVIIA were first screened in a number of mollusc or vertebrate electrophysiological preparations.

Consistent effects were observed on caudodorsal neurons from the snail Lymnaea stagnalis, and this system was therefore used for detailed investigations on toxin activity. The caudodorsal neurons are typical rythmic bursting cells responsible for production of egg laying hormone, and their ionic currents have been characterized exhaustively (Brussaard et al., 1991; Dreijer & Kits, 1995; Kits & Mansvelder, 1996). In the first series of experiments, PnVIIA was applied to caudodorsal neurons recorded under current clamp and the effects on membrane potential and action potential firing were investigated. It was found that PnVIIA enhances the excitability of these cells in a dose-dependent way. Thus, a dose-dependent increase in excitability of caudodorsal cells (CDCs), inducing depolarization and repetitive spiking upon application of micromolar doses of PnVIIA was seen. Cells that were silent responded to low doses (<1 μM) of the toxin by depolarization, while doses of 10 μM or more induced trains of action potentials. The number of action potentials increased with increasing doses. The duration of PnVIIA application also markedly influenced the response. In silent cells, responding with a burst of action potentials, the number of action potentials and the duration of the burst increased with increasing duration of the PnVIIA pulse. Thus, a time dependence of the excitatory effect of PnVIIA in silent CDCs, showing increased duration of spiking with increased duration of application was seen. Cells that were spontaneously active responded by a temporary increase in firing frequency, followed by an afterburst hyperpolarization during which the cell stops firing for a short period. Increasing the duration of PnVIIA application under these circumstances led to an increase in the duration of the burst, but even more so in the duration of the afterburst silent refractory period. Thus, a time dependence of the excitatory effect of PnVIIA in spontaneously active CDCs, showing that not only spiking increases but also the duration of silent period after the afterburst increases with longer applications was seen. The latter effect is possibly indirect, as a natural consequence from the increased firing frequency induced by the toxin.

Whether the effect was due to closure (blockade) or opening (activation) of ion channels was investigated by measuring input resistance of the cell membrane upon injection of hyperpolarizing current pulses (30 μA). The amplitude of the resulting hyperpolarization is a direct measure of the membrane resistance. In this experiment, pulses of hyperpolarizing current were injected into CDCs, giving rise to hyperpolarizations of the membrane potential. While the injected current is constant, the hyperpolarizing response decreases upon application of PnVIIA, showing that the membrane resistance decreases or, in other words, the membrane conductance increases. It was seen that during PnVIIA application hyperpolarization amplitude is strongly decreased (˜50% attenuation), thus revealing a marked decrease in membrane resistance. Thus, PnVIIA induces an increase in conduction, i.e., leads to the opening of ion channels, and therefore acts primarily as a channel agonist or activator, rather than as a channel blocker.

In a further series of experiments, the identity of the channel(s) activated by PnVIIA was investigated. To this end, whole cell voltage clamp experiments were performed on caudodorsal neurons, however, no consistent effects of the toxin could be observed on fast voltage gated sodium or calcium currents, nor on the potassium currents that are activated in a standard voltage step protocol. A slow ramp protocol was then applied to investigate possible effects on slow voltage gated currents (also designated as pacemaker currents) that are believed to underlie spontaneous firing. In this experiment current responses to a voltage ramp protocol in standard HBS during which the membrane potentials go from −80 to +20 mV at a rate of mV/s (control) were measured. This protocol will only reveal slow, voltage-gated currents, as fast currents will inactivate during the slow voltage ramp. An inward current is activated at ˜−30 mV and more positive. Most likely, this represents a pacemaker current. With 10 μM PnVIIA (10 μM) the voltage dependence shifts to the left (i.e., the current activates already at more hyperpolarized potentials). Furthermore, an increase in outward current at >˜0 mV occurs. Thus, the experiments indicated that a noninactivating inward current is activated at voltages above 30 mV to the voltage ramp protocol. Preliminary experiments indicate that this inward current is a nonspecific cation current that is reduced in Na⁺ free selective saline and completely blocked by 1 mM Ni²+. Thus, most likely, Na⁺ and Ca²⁺ carry the inward current. In voltage dependence and ion selectivity, this current strongly resembles a pacemaker current in other Lymnaea neurons elaborately described by van Soest and Kits (1997). In the presence of 10 μM PnVIIA, a dual effect was observed. First, the activation range of the slow inward current shifted by ˜10 mV to a more negative potential, thus accounting for the enhanced excitability of the cells. Second, we saw an increase in noninactivating outward current at potentials above 0 mV. Whether the latter is a direct effect of PnVIIA, or an indirect effect due to the increased inward current, remains to be determined. It is, however, in line with the previously observed prolongation of afterburst hyperpolarization under current clamp conditions. These data show that the primary event mediating the excitatory effects of PnVIIA on Lymnaea caudodorsal neurons is an enhancement of a slow, voltage-activated inward cation channel.

Example 5 Isolation of a γ-Conotoxin Tx6.4 from Conus textile

A Conus textile cDNA library was prepared from venom duct using conventional techniques. DNA from single clones was amplified by conventional techniques using primers which correspond approximately to the M13 universal priming site and the M13 reverse universal priming site. The primers which were used are:

5′-TTTCCCAGTCACGACGTT-3′ (SEQ ID NO:46) and

5′-CACACAGGAAACAGCTATG-3′ (SEQ ID NO:47).

Clones having a size of approximately 300 nucleotides were sequenced and screened for similarity in sequence to PnVIIA and TxVIIA. A DNA was isolated having the sequence set forth in SEQ ID NO: 16, which encoded the propeptide sequence set forth in SEQ ID NO: 17. This new γ-conotoxin has the sequence described above and set forth in SEQ ID NO:7. Preferably, Xaa₁ is Trp, Xaa₂ is γ-Glu and Xaa₃ is Hyp. The C-terminus preferably contains a free hydroxyl group.

Example 6 Isolation of γ-Conopeptides

The procedure of Example 5 was followed to isolate additional nucleic acids encoding γ-conopeptides. The nucleic acids which were isolated have the nucleotide sequences set forth in SEQ ID NOs: 18, 20, 22, 24, 26, 28, 30, 32 and 34. These nucleic acids encode the propeptides having the amino acid sequences set forth in SEQ ID NOs:19, 21, 23, 25, 27, 29, 31, 33 and 35, respectively. The mature peptide sequences are set forth in SEQ ID NOs:8-15 and 36.

Example 7 Biological Activity of γ-Conotoxin TxVIIA

Isolated medial neurons from Aplysia oculifera pleuropedal ganglia (Kehoe, 1972) were cultured as previously described (Schacher & Proshansky, 1983). The neurons were cultured at very low densities to prevent any possible synaptic interactions among them. Passive and active membrane properties of the cultured neurons were studied using conventional intracellular recording and stimulation techniques. Briefly, the cell body of a cultured neuron was impaled by two microelectrodes filled with 2 M KCl (5-10 MΩ resistance), one for current injection and the other for voltage recording. Analysis of the resting potential, input resistance, and action potential amplitude and shape was carried out in artificial sea water composed of 460 nM NaCl, 10 mM KCl, 11 mM CaCl₂, 55 mM MgCl₂ and 10 mM Hepes, pH 7.6. Venom fractions for electrophysiological experiments were dissolved in artificial sea water containing 10 mg/ml bovine serum albumin. The Sephadex™ G-50 fraction was applied at 100-200 μg/ml and purified toxin at final concentrations of 0.25-0.5 μM.

The effects of venom fractions and purified toxin on isolated Aplysia neurons were characterized by measuring the resting potential, input resistance and action potential amplitude and shape. The Vt fraction from the Sephadex™ G-50 column (G-50-Vt) (Fainzilber et al., 1991) and the purified toxin revealed significant effects at concentrations of 100 μg/ml and 0.25-0.5 μM, respectively. The effects of G-50-Vt, TxIA and TxIB were essentially similar Fainzilber et al., 1991). These fractions induced a transient membrane depolarization of 5-12 mV for 40-120 s. Within 3-30 s. after bath application of the toxin, the quiescent neurons fired spontaneously. Concomitantly, the action potential duration increased by one to two orders of magnitude, extending in many experiments to over 1 s. The prolonged action potentials are typically composed of an initial spike with a prolonged shoulder. In the continuous presence of the toxin in the bathing solution, the action potential duration gradually recovers. 20-30 min. after toxin application, the action potential duration was only 50-100% longer than in the control. Throughout this period, the threshold for action potential initiation was reduced. The changes in membrane excitability and action potential duration induced by the toxins were completely reversible upon washing of the neuron with artificial sea water. TxI-induced prolongation of the action potential duration was observed also when Ca²⁺ and K⁺ conductances were blocked (Ca²⁺ free artificial sea water, 16 mM Ca²⁺ and 50 mM tetraethylammonium, 150 μM 3,4-diaminopyridine and 10 nM Cs). Addition of tetrodotoxin (10 μM) under these conditions reduced the TxI-induced spike prolongation. TxVIIA induced similar effects on the membrane properties of isolated neurons, including membrane depolarization and repetitive firing. However, TxVIIA did not cause any increase in action potential duration.

The amino acid sequence of PnVIIA conserves the six-cysteine, four-loop framework C . . . C . . . CC . . . C . . . C typical of ω and δ conotoxins, and as shown in Table 4, is most homologous to the sequence of conotoxin-TxVIIA, an excitatory toxin from Conus textile venom (Fainziber et al., 1991; Nakarnura et al., 1996). Both of these toxins have an identical, extremely acidic net charge (−5) and are similar in their surface hydrophobic/hydrophilic interaction properties, as evidenced by comparable elusion properties in reverse-phase chromatography. Furthermore, the grow effects of these toxins in their respective sensitive systems (Aplysia versus Lymnaea neurons) are very similar, comprising an enhancement of excitability decreased membrane resistance, and increased repetitive firing. PnVIIA and TxVIIA may therefore represent closely related members of the same family, or convergent evolution to closely related receptor/channel targets.

The paralytic activities of both TxVIIA and PnVIIA in their respective bioassays are markedly decreased upon decarboxylation of the γGlu residues. Although the primarily structural importance of γGlu-metal chelates in mammalian vitamin K-dependent blood coagulation proteins and in mollusc conantokins is well established (Freedman et al., 1995; Skjaerbaek et al., 1997), there is also evidence, for example, in prothrombin of a functional role of individual γGlu residues in membrane binding (Ratcliffe et al., 1993). Although the 3-D structures of conotokins TxVIIA and γPnVIIA are most likely directed and stabilized by the three disulfide bonds, as in conotoxins in general, we cannot rule out at this stage a secondary microstructural role of the γGlu residues. However, an attractive hypothesis is that the γGlu residues in these peptides form part of a membrane or receptor recognition patch, with other variable residues (Table 4) providing specific recognition for channel isoforms or subtypes. Hypervariability in structurally related conotoxins is a well established mediator of the exquisite selectivity of these peptides for receptor subtypes (Myers et al., 1993; Nielsen et al., 1996).

It will be appreciated that the methods and compositions of the instant invention can be incorporated in the form of a variety of embodiments, only a few of which are disclosed herein. It will be apparent to the artisan that other embodiments exist and do not depart from the spirit of the invention. Thus, the described embodiments are illustrative and should not be construed as restrictive.

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PCT Published Application WO 96/11698

47 1 42 PRT Artificial Sequence Description of Artificial Sequencegeneric formula of gamma-conopeptides 1 Xaa Xaa Xaa Xaa Xaa Xaa Cys Xaa Xaa Xaa Xaa Xaa Xaa Cys Xaa Xaa 1 5 10 15 Xaa Xaa Xaa Cys Cys Xaa Xaa Xaa Xaa Cys Xaa Xaa Xaa Xaa Xaa Xaa 20 25 30 Cys Xaa Xaa Xaa Xaa Xaa Xaa Xaa Xaa Xaa 35 40 2 42 PRT Artificial Sequence Description of Artificial Sequencegeneric sequence of gamma-conopeptides. 2 Xaa Xaa Xaa Xaa Xaa Xaa Cys Xaa Xaa Xaa Xaa Xaa Xaa Cys Xaa Xaa 1 5 10 15 Xaa Xaa Xaa Cys Cys Xaa Xaa Xaa Xaa Cys Xaa Xaa Xaa Xaa Xaa Xaa 20 25 30 Cys Xaa Xaa Xaa Xaa Xaa Xaa Xaa Xaa Xaa 35 40 3 39 PRT Artificial Sequence Description of Artificial Sequencegeneric formula of gamma-conopeptides 3 Xaa Xaa Xaa Xaa Xaa Xaa Cys Xaa Xaa Xaa Xaa Xaa Xaa Cys Xaa Xaa 1 5 10 15 Xaa Xaa Xaa Cys Cys Ser Asn Ser Cys Asp Xaa Xaa Xaa Cys Xaa Xaa 20 25 30 Xaa Xaa Xaa Xaa Xaa Xaa Xaa 35 4 39 PRT Artificial Sequence Description of Artificial Sequencegeneric sequence of gamma-conopeptides. 4 Xaa Xaa Xaa Xaa Xaa Xaa Cys Xaa Xaa Xaa Xaa Xaa Xaa Cys Xaa Xaa 1 5 10 15 Xaa Xaa Xaa Cys Cys Ser Asn Ser Cys Asp Xaa Xaa Xaa Cys Xaa Xaa 20 25 30 Xaa Xaa Xaa Xaa Xaa Xaa Xaa 35 5 34 PRT Artificial Sequence Description of Artificial Sequencegeneric sequence of gamma-conopeptides. 5 Xaa Xaa Xaa Cys Xaa Xaa Xaa Phe Xaa Xaa Cys Thr Xaa Xaa Ser Xaa 1 5 10 15 Cys Cys Ser Asn Ser Cys Asp Trp Thr Tyr Cys Xaa Leu Xaa Xaa Xaa 20 25 30 Xaa Xaa 6 32 PRT Conus pennaceus PEPTIDE (1)..(31) Xaa at residue 5 is Trp or 6-bromo-Trp; Xaa at residues 14 and 26 are Glu or gamma-carboxyglutamate; Xaa at residue 31 is Pro or hydroxy-Pro. 6 Asp Cys Thr Ser Xaa Phe Gly Arg Cys Thr Val Asn Ser Xaa Cys Cys 1 5 10 15 Ser Asn Ser Cys Asp Gln Thr Tyr Cys Xaa Leu Tyr Ala Phe Xaa Ser 20 25 30 7 34 PRT Conus textile PEPTIDE (1)..(34) Xaa at residues 1, 7 and 34 are Trp or 6-bromo-Trp; Xaa at residues 3 and 16 are Glu or gamma-carboxyglutamate; Xaa at residues 31 and 32 are Pro or hydroxy-Pro. 7 Xaa Leu Xaa Cys Ser Val Xaa Phe Ser His Cys Thr Lys Asp Ser Xaa 1 5 10 15 Cys Cys Ser Asn Ser Cys Asp Gln Thr Tyr Cys Thr Leu Met Xaa Xaa 20 25 30 Asp Xaa 8 39 PRT Conus textile PEPTIDE (1)..(39) Xaa at residues 1, 2, 4, 10 and 39 are Trp or 6-bromo-Trp ; Xaa at residues 19 and 31 are Glu or gammacarboxyglutamate; Xaa at residues 34, 36 and 37 ar Pro or hydroxy-Pro. 8 Xaa Xaa Arg Xaa Gly Gly Cys Met Ala Xaa Phe Gly Leu Cys Ser Arg 1 5 10 15 Asp Ser Xaa Cys Cys Ser Asn Ser Cys Asp Val Thr Arg Cys Xaa Leu 20 25 30 Met Xaa Phe Xaa Xaa Asp Xaa 35 9 27 PRT Conus textile PEPTIDE (1)..(27) Xaa at residues 9, 13 and 17 are Glu or gamma-carboxyglutamate. 9 Cys Lys Thr Tyr Ser Lys Tyr Cys Xaa Ala Asp Ser Xaa Cys Cys Thr 1 5 10 15 Xaa Gln Cys Val Arg Ser Tyr Cys Thr Leu Phe 20 25 10 34 PRT Conus textile PEPTIDE (1)..(34) Xaa at residues 2, 3, 10 and 32 are Trp or 6-bromo-Trp; Xaa at residues 18, 26 and 33 are Glu or gamma-carboxyglutamate; Xaa at residue 12 is Pro or hydroxy-Pro. 10 Asp Xaa Xaa Asp Asp Gly Cys Ser Val Xaa Gly Xaa Cys Thr Tyr Asn 1 5 10 15 Ala Xaa Cys Cys Ser Gly Asp Cys His Xaa Thr Cys Ile Phe Gly Xaa 20 25 30 Xaa Val 11 31 PRT Conus textile PEPTIDE (1)..(31) Xaa at residues 3 and 31 are Trp of 6-bromo-Trp; Xaa at residues 5, 18, 22 and 25 are Glu or gamma-carboxyglutamate; Xaa at residue 16 is Pro or hydroxy-Pro. 11 Gly Met Xaa Gly Xaa Cys Lys Asp Gly Leu Thr Thr Cys Leu Ala Xaa 1 5 10 15 Ser Xaa Cys Cys Ser Xaa Asp Cys Xaa Gly Ser Cys Thr Met Xaa 20 25 30 12 32 PRT Conus gloriamaris PEPTIDE (1)..(32) Xaa at residue 5 is Trp or 6-bromo-Trp; Xaa at residue 1 is Glu or gamma-carboxyglutamate; Xaa at residues 8 and 11 are Pro or hydroxy-Pro. 12 Xaa Cys Arg Ala Xaa Tyr Ala Xaa Cys Ser Xaa Gly Ala Gln Cys Cys 1 5 10 15 Ser Leu Leu Met Cys Ser Lys Ala Thr Ser Arg Cys Ile Leu Ala Leu 20 25 30 13 29 PRT Conus marmoreus PEPTIDE (1)..(29) Xaa at residues 8 and 15 are Trp or 6-bromo-Trp; Xaa at residues 5, 16 and 23 are Glu or gamma-carboxyglutamate; Xaa at residue 10 is Pro or hydroxy-Pro. 13 Asn Gly Gln Cys Xaa Asp Val Xaa Met Xaa Cys Thr Ser Asn Xaa Xaa 1 5 10 15 Cys Cys Ser Leu Asp Cys Xaa Met Tyr Cys Thr Gln Ile 20 25 14 27 PRT Conus marmoreus PEPTIDE (1)..(27) Xaa at residue 4 is Trp or 6-bromo-Trp; Xaa at residues 9, 12, 13 and 17 are Glu or gamma-carboxyglutamate. 14 Cys Gly Gly Xaa Ser Thr Tyr Cys Xaa Val Asp Xaa Xaa Cys Cys Ser 1 5 10 15 Xaa Ser Cys Val Arg Ser Tyr Cys Thr Leu Phe 20 25 15 26 PRT Conus marmoreus PEPTIDE (1)..(26) Xaa at residues 8 and 15 are Trp or 6-bromo-Trp; Xaa at residue 16 is Glu or gamma-carboxyglutamate. 15 Asn Gly Gly Cys Lys Ala Thr Xaa Met Ser Cys Ser Ser Gly Xaa Xaa 1 5 10 15 Cys Cys Ser Met Ser Cys Asp Met Tyr Cys 20 25 16 323 DNA Conus textile CDS (1)..(153) 16 gaa cgg gct aag atc aac ttg ctt cca aag aga aag cca cct gct gag 48 Glu Arg Ala Lys Ile Asn Leu Leu Pro Lys Arg Lys Pro Pro Ala Glu 1 5 10 15 cgt tgg ttg gaa tgc agt gtt tgg ttt tca cat tgt acg aag gac tcg 96 Arg Trp Leu Glu Cys Ser Val Trp Phe Ser His Cys Thr Lys Asp Ser 20 25 30 gaa tgt tgt tct aat agt tgt gac caa acg tac tgc acg tta atg cca 144 Glu Cys Cys Ser Asn Ser Cys Asp Gln Thr Tyr Cys Thr Leu Met Pro 35 40 45 ccg gac tgg tgacatcgcc actctcctgt tcagagtctt caaggctttt 193 Pro Asp Trp 50 gttctctttt gaagaatttt aacgagtgaa caaaaaagtg gactagcatg tttccttttc 253 cctttgcaaa atcaatgatg gaggtaaaag cctcccattt tgtcttcatc aataaagaac 313 ttatcatcat 323 17 51 PRT Conus textile 17 Glu Arg Ala Lys Ile Asn Leu Leu Pro Lys Arg Lys Pro Pro Ala Glu 1 5 10 15 Arg Trp Leu Glu Cys Ser Val Trp Phe Ser His Cys Thr Lys Asp Ser 20 25 30 Glu Cys Cys Ser Asn Ser Cys Asp Gln Thr Tyr Cys Thr Leu Met Pro 35 40 45 Pro Asp Trp 50 18 510 DNA Conus textile CDS (95)..(337) 18 tgactcgcca tctcctctct cagtctccct gacagctgcc ttcagtcgac cctgccgtca 60 tctcaacgca cacttgaagt gaaaaacctt tatc atg gag aaa ctg aca att ctg 115 Met Glu Lys Leu Thr Ile Leu 1 5 ctt ctt gtt gct gct gta ctg ttg tcg atc cag gcc cta aat caa gaa 163 Leu Leu Val Ala Ala Val Leu Leu Ser Ile Gln Ala Leu Asn Gln Glu 10 15 20 aaa cac caa cgg gca aag atc aac ttg ctt tca aag aga aag cca cct 211 Lys His Gln Arg Ala Lys Ile Asn Leu Leu Ser Lys Arg Lys Pro Pro 25 30 35 gct gag cgt tgg tgg cgg tgg gga gga tgc atg gct tgg ttt ggg ctt 259 Ala Glu Arg Trp Trp Arg Trp Gly Gly Cys Met Ala Trp Phe Gly Leu 40 45 50 55 tgt tcg agg gac tcg gaa tgt tgt tct aat agt tgt gac gta acg cgc 307 Cys Ser Arg Asp Ser Glu Cys Cys Ser Asn Ser Cys Asp Val Thr Arg 60 65 70 tgc gag tta atg cca ttc cca cca gac tgg tgacatcgac actctcctct 357 Cys Glu Leu Met Pro Phe Pro Pro Asp Trp 75 80 tcagagtctt caaggctttt gttctctttt gaagaatttt tacgagtgaa caaaaacgtg 417 gactagcacg tttccttttc cctttgcaaa atcaatgatg gaggtaaaag tgtcccattt 477 tgtcttcatc aataaagaac ttatcatcat aat 510 19 81 PRT Conus textile 19 Met Glu Lys Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Leu Ser 1 5 10 15 Ile Gln Ala Leu Asn Gln Glu Lys His Gln Arg Ala Lys Ile Asn Leu 20 25 30 Leu Ser Lys Arg Lys Pro Pro Ala Glu Arg Trp Trp Arg Trp Gly Gly 35 40 45 Cys Met Ala Trp Phe Gly Leu Cys Ser Arg Asp Ser Glu Cys Cys Ser 50 55 60 Asn Ser Cys Asp Val Thr Arg Cys Glu Leu Met Pro Phe Pro Pro Asp 65 70 75 80 Trp 20 441 DNA Conus textile CDS (16)..(243) 20 ggaaaaactt ttatc atg gag aaa ctg aca atc ctg ctc ctt gtt gct gct 51 Met Glu Lys Leu Thr Ile Leu Leu Leu Val Ala Ala 1 5 10 gta ctg atg tcg acc cag gcc atg ttt caa ggt gat gga gaa aaa tcc 99 Val Leu Met Ser Thr Gln Ala Met Phe Gln Gly Asp Gly Glu Lys Ser 15 20 25 cgg aag gcg gag atc aac ttt tct gaa aca aga aag ttg gcg aga aac 147 Arg Lys Ala Glu Ile Asn Phe Ser Glu Thr Arg Lys Leu Ala Arg Asn 30 35 40 aag cag aaa cgc tgc aaa act tat tca aag tat tgt gaa gct gac tcg 195 Lys Gln Lys Arg Cys Lys Thr Tyr Ser Lys Tyr Cys Glu Ala Asp Ser 45 50 55 60 gaa tgc tgt acc gaa cag tgt gta agg tct tac tgc acg ttg ttt gga 243 Glu Cys Cys Thr Glu Gln Cys Val Arg Ser Tyr Cys Thr Leu Phe Gly 65 70 75 tgaattcgga ccacaagcca tccgatatca cccctctcct cttcagaggc ttcaaggctt 303 ttgttatcct tttgaagaat ctttatcgag taaacataag tagacaagct ttttttttcc 363 tttgcaaaat gaagaatgat ggcaaaaagc cccccatttt gtcttcatca ataaagaact 423 cgctatcaga ataaaaaa 441 21 76 PRT Conus textile 21 Met Glu Lys Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Met Ser 1 5 10 15 Thr Gln Ala Met Phe Gln Gly Asp Gly Glu Lys Ser Arg Lys Ala Glu 20 25 30 Ile Asn Phe Ser Glu Thr Arg Lys Leu Ala Arg Asn Lys Gln Lys Arg 35 40 45 Cys Lys Thr Tyr Ser Lys Tyr Cys Glu Ala Asp Ser Glu Cys Cys Thr 50 55 60 Glu Gln Cys Val Arg Ser Tyr Cys Thr Leu Phe Gly 65 70 75 22 460 DNA Conus textile CDS (49)..(273) 22 ctgccgtcat ctcagcgcac acttggtaag aagtgaaaaa ccttgatc atg gag aaa 57 Met Glu Lys 1 ctg aca att ctg ctt ctt gtt gct gct gtg ctg atg tcg acc cag gcc 105 Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Met Ser Thr Gln Ala 5 10 15 cta att caa gat caa cgc caa aag gca aag atc aac ttg ttt tca aag 153 Leu Ile Gln Asp Gln Arg Gln Lys Ala Lys Ile Asn Leu Phe Ser Lys 20 25 30 35 aga cag gca tat gct cgt gat tgg tgg gac gat ggc tgc agt gtg tgg 201 Arg Gln Ala Tyr Ala Arg Asp Trp Trp Asp Asp Gly Cys Ser Val Trp 40 45 50 ggg cct tgt acg gtg aac gca gaa tgt tgt tct ggt gat tgt cat gaa 249 Gly Pro Cys Thr Val Asn Ala Glu Cys Cys Ser Gly Asp Cys His Glu 55 60 65 acg tgc att ttc ggg tgg gaa gtc tgaccacaaa ccatccgaca tcgccactct 303 Thr Cys Ile Phe Gly Trp Glu Val 70 75 cctcttcaga gacttcaagg cttttgttct cttttgaaga attttacgag tgagcaaaaa 363 ggtagactag cacgtttctt tttccctttg caaaatcaat gatggaggta aaagcctccc 423 attttgtcct catcaataaa gaacttatca tcataat 460 23 75 PRT Conus textile 23 Met Glu Lys Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Met Ser 1 5 10 15 Thr Gln Ala Leu Ile Gln Asp Gln Arg Gln Lys Ala Lys Ile Asn Leu 20 25 30 Phe Ser Lys Arg Gln Ala Tyr Ala Arg Asp Trp Trp Asp Asp Gly Cys 35 40 45 Ser Val Trp Gly Pro Cys Thr Val Asn Ala Glu Cys Cys Ser Gly Asp 50 55 60 Cys His Glu Thr Cys Ile Phe Gly Trp Glu Val 65 70 75 24 533 DNA Conus textile CDS (110)..(337) 24 ctctgccggt tgacacntca tctactctct cagtctccct gacagctgcc ttcagtcgac 60 cctgccgtca tctcagcgca gacttgataa gaagtgaaaa acctttatc atg gag aaa 118 Met Glu Lys 1 ctg aca atc ctg ctt ctt gtt gct gct gta ctg atg tcg acc cag gcc 166 Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Met Ser Thr Gln Ala 5 10 15 ctg gtt gaa cgt gct gga gaa aac cac tca aag gag aac atc aat ttt 214 Leu Val Glu Arg Ala Gly Glu Asn His Ser Lys Glu Asn Ile Asn Phe 20 25 30 35 tta tta aaa aga aag aga gct gct gac agg ggg atg tgg ggc gaa tgc 262 Leu Leu Lys Arg Lys Arg Ala Ala Asp Arg Gly Met Trp Gly Glu Cys 40 45 50 aaa gat ggg tta acg aca tgt ttg gcg ccc tca gag tgt tgt tct gag 310 Lys Asp Gly Leu Thr Thr Cys Leu Ala Pro Ser Glu Cys Cys Ser Glu 55 60 65 gat tgt gaa ggg agc tgc acg atg tgg tgatgaattc tgaccacaag 357 Asp Cys Glu Gly Ser Cys Thr Met Trp 70 75 ccatctgaca tcaccactct cctcttcaga ggcttcaagg cttttgtttt ccttttgaat 417 aatctttacg agtaaacaaa taagtagact agcgcgtttt tttccctttg agaaatcaat 477 gatggaggta aatagcttcc tattttgtct tattcaataa agaacttatc ataata 533 25 76 PRT Conus textile 25 Met Glu Lys Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Met Ser 1 5 10 15 Thr Gln Ala Leu Val Glu Arg Ala Gly Glu Asn His Ser Lys Glu Asn 20 25 30 Ile Asn Phe Leu Leu Lys Arg Lys Arg Ala Ala Asp Arg Gly Met Trp 35 40 45 Gly Glu Cys Lys Asp Gly Leu Thr Thr Cys Leu Ala Pro Ser Glu Cys 50 55 60 Cys Ser Glu Asp Cys Glu Gly Ser Cys Thr Met Trp 65 70 75 26 408 DNA Conus gloriamaris CDS (2)..(211) 26 g ctg aca atc ctg ctt ctt gtt gct gct gta ctg atg tcg acc cag gcc 49 Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Met Ser Thr Gln Ala 1 5 10 15 ctg att caa ggt ggt ggt gac aaa cgt caa aag gca aac atc aac ttt 97 Leu Ile Gln Gly Gly Gly Asp Lys Arg Gln Lys Ala Asn Ile Asn Phe 20 25 30 ctt tca agg tgg gac cgt gag tgc agg gct tgg tat gcg ccg tgt agc 145 Leu Ser Arg Trp Asp Arg Glu Cys Arg Ala Trp Tyr Ala Pro Cys Ser 35 40 45 cct ggc gcg caa tgt tgt agt ttg ctg atg tgt tca aaa gcg acc agc 193 Pro Gly Ala Gln Cys Cys Ser Leu Leu Met Cys Ser Lys Ala Thr Ser 50 55 60 cgc tgc ata ttg gcg tta tgaactctga ccacaagcca tccgacatca 241 Arg Cys Ile Leu Ala Leu 65 70 ccactctcct cttcagaggc ttcaaggctt tttgtttttc ttttgaagaa tctttacgag 301 tgaacaaata agtagaatag cacgtttttc cccctttgca aaatcaataa tggaggttaa 361 aaaaaaactt ctgtcttctt caataaagaa gttatcataa taaaaaa 408 27 70 PRT Conus gloriamaris 27 Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Met Ser Thr Gln Ala 1 5 10 15 Leu Ile Gln Gly Gly Gly Asp Lys Arg Gln Lys Ala Asn Ile Asn Phe 20 25 30 Leu Ser Arg Trp Asp Arg Glu Cys Arg Ala Trp Tyr Ala Pro Cys Ser 35 40 45 Pro Gly Ala Gln Cys Cys Ser Leu Leu Met Cys Ser Lys Ala Thr Ser 50 55 60 Arg Cys Ile Leu Ala Leu 65 70 28 278 DNA Conus marmoreus CDS (4)..(222) 28 atc atg cag aaa ctg ata atc ctg ctt ctt gtt gct gct gtg ctg ctg 48 Met Gln Lys Leu Ile Ile Leu Leu Leu Val Ala Ala Val Leu Leu 1 5 10 15 tcg acc cag gcc cta aat caa gaa aaa cgc cca aag gag atg atc aat 96 Ser Thr Gln Ala Leu Asn Gln Glu Lys Arg Pro Lys Glu Met Ile Asn 20 25 30 ttt tta tca aaa gga aag aca aat gct gag agg cgg aac ggc caa tgc 144 Phe Leu Ser Lys Gly Lys Thr Asn Ala Glu Arg Arg Asn Gly Gln Cys 35 40 45 gag gat gtt tgg atg cct tgt aca tcg aac tgg gaa tgc tgt tct ttg 192 Glu Asp Val Trp Met Pro Cys Thr Ser Asn Trp Glu Cys Cys Ser Leu 50 55 60 gat tgt gaa atg tac tgc aca cag ata gga tgaactctga ccacaagcca 242 Asp Cys Glu Met Tyr Cys Thr Gln Ile Gly 65 70 tccgacatca ccactctcct cttcagagtc ttcaag 278 29 73 PRT Conus marmoreus 29 Met Gln Lys Leu Ile Ile Leu Leu Leu Val Ala Ala Val Leu Leu Ser 1 5 10 15 Thr Gln Ala Leu Asn Gln Glu Lys Arg Pro Lys Glu Met Ile Asn Phe 20 25 30 Leu Ser Lys Gly Lys Thr Asn Ala Glu Arg Arg Asn Gly Gln Cys Glu 35 40 45 Asp Val Trp Met Pro Cys Thr Ser Asn Trp Glu Cys Cys Ser Leu Asp 50 55 60 Cys Glu Met Tyr Cys Thr Gln Ile Gly 65 70 30 287 DNA Conus marmoreus CDS (4)..(231) 30 atc atg gag aaa ctg aca atc ctg ctt ctt gtt gct gct gta ctg ata 48 Met Glu Lys Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Ile 1 5 10 15 ccg acc cag gcc ctt ttt caa ggt gat gac gga aaa tcc cag aag gcg 96 Pro Thr Gln Ala Leu Phe Gln Gly Asp Asp Gly Lys Ser Gln Lys Ala 20 25 30 gag atc aag tct ttt gaa aca aga aag tta gcg aga aac aag cag gta 144 Glu Ile Lys Ser Phe Glu Thr Arg Lys Leu Ala Arg Asn Lys Gln Val 35 40 45 cgc tgc ggt ggt tgg tca acg tat tgt gaa gtt gac gag gaa tgc tgt 192 Arg Cys Gly Gly Trp Ser Thr Tyr Cys Glu Val Asp Glu Glu Cys Cys 50 55 60 tcg gaa tca tgt gta agg tct tac tgc acg ctg ttt gga tgaactcgga 241 Ser Glu Ser Cys Val Arg Ser Tyr Cys Thr Leu Phe Gly 65 70 75 ccacaagcca tccgatatca ccactctcct gttcagagtc ttcaag 287 31 76 PRT Conus marmoreus 31 Met Glu Lys Leu Thr Ile Leu Leu Leu Val Ala Ala Val Leu Ile Pro 1 5 10 15 Thr Gln Ala Leu Phe Gln Gly Asp Asp Gly Lys Ser Gln Lys Ala Glu 20 25 30 Ile Lys Ser Phe Glu Thr Arg Lys Leu Ala Arg Asn Lys Gln Val Arg 35 40 45 Cys Gly Gly Trp Ser Thr Tyr Cys Glu Val Asp Glu Glu Cys Cys Ser 50 55 60 Glu Ser Cys Val Arg Ser Tyr Cys Thr Leu Phe Gly 65 70 75 32 278 DNA Conus marmoreus CDS (4)..(213) 32 atc atg cag aaa ctg ata att ctg ctt ctt gtt gct gct gtg ctg atg 48 Met Gln Lys Leu Ile Ile Leu Leu Leu Val Ala Ala Val Leu Met 1 5 10 15 acg acc cag gcc cta tat caa gaa aaa cgc cga aag gag atg atc aat 96 Thr Thr Gln Ala Leu Tyr Gln Glu Lys Arg Arg Lys Glu Met Ile Asn 20 25 30 ttt tta tca aaa gga aag ata aat gct gag agg cgg aac ggc gga tgc 144 Phe Leu Ser Lys Gly Lys Ile Asn Ala Glu Arg Arg Asn Gly Gly Cys 35 40 45 aaa gct act tgg atg tct tgt tca tcg ggc tgg gaa tgc tgt tct atg 192 Lys Ala Thr Trp Met Ser Cys Ser Ser Gly Trp Glu Cys Cys Ser Met 50 55 60 agt tgt gac atg tac tgc gga tagataggat gaactctgac cacaagccat 243 Ser Cys Asp Met Tyr Cys Gly 65 70 ccgacatcac cactctcctc ttcagagtct tcaag 278 33 70 PRT Conus marmoreus 33 Met Gln Lys Leu Ile Ile Leu Leu Leu Val Ala Ala Val Leu Met Thr 1 5 10 15 Thr Gln Ala Leu Tyr Gln Glu Lys Arg Arg Lys Glu Met Ile Asn Phe 20 25 30 Leu Ser Lys Gly Lys Ile Asn Ala Glu Arg Arg Asn Gly Gly Cys Lys 35 40 45 Ala Thr Trp Met Ser Cys Ser Ser Gly Trp Glu Cys Cys Ser Met Ser 50 55 60 Cys Asp Met Tyr Cys Gly 65 70 34 528 DNA Conus textile CDS (98)..(316) 34 gcacgtcatc ttctctctca gtctgcctga cagctgcctt cagtcaaccc tgccgtcatc 60 tcagcgtaga cttggtaaga agtgaaaaac atttatc atg cag aaa ctg ata atc 115 Met Gln Lys Leu Ile Ile 1 5 ctg ctt ctt gtt gct gct gtg ctg atg tcg acc cag gcc gtg ctt caa 163 Leu Leu Leu Val Ala Ala Val Leu Met Ser Thr Gln Ala Val Leu Gln 10 15 20 gaa aaa cgc cca aag gag aag atc aag ctt tta tca aag aga aag aca 211 Glu Lys Arg Pro Lys Glu Lys Ile Lys Leu Leu Ser Lys Arg Lys Thr 25 30 35 gat gct gag aag cag cag aag cgc ctt tgc ccg gat tac acg gag cct 259 Asp Ala Glu Lys Gln Gln Lys Arg Leu Cys Pro Asp Tyr Thr Glu Pro 40 45 50 tgt tca cat gcc cat gaa tgc tgt tca tgg aat tgt tat aat ggg cac 307 Cys Ser His Ala His Glu Cys Cys Ser Trp Asn Cys Tyr Asn Gly His 55 60 65 70 tgt acg gga tgaactcgga ccacaagcca tccgacatca ccactctcct 356 Cys Thr Gly cttcagaggc ttcaagactt ttgttctgat tttggacaat ctttacgagt aaacaaataa 416 ttagactagc actttttttc ccctttgcaa aatcaatgat ggaggtaaaa agcctcccat 476 tttgtcttca tcaataaaga acttatcatc aaaaaaaaaa aaaaaaaaaa aa 528 35 73 PRT Conus textile 35 Met Gln Lys Leu Ile Ile Leu Leu Leu Val Ala Ala Val Leu Met Ser 1 5 10 15 Thr Gln Ala Val Leu Gln Glu Lys Arg Pro Lys Glu Lys Ile Lys Leu 20 25 30 Leu Ser Lys Arg Lys Thr Asp Ala Glu Lys Gln Gln Lys Arg Leu Cys 35 40 45 Pro Asp Tyr Thr Glu Pro Cys Ser His Ala His Glu Cys Cys Ser Trp 50 55 60 Asn Cys Tyr Asn Gly His Cys Thr Gly 65 70 36 26 PRT Conus textile PEPTIDE (1)..(26) Xaa at residue 18 is Trp or 6-bromo-Trp; Xaa at residues 7 and 14 are Glu or gamma-carboxyglutamate; Xaa at residues 3 and 8 are Pro or hydroxy-Pro. 36 Leu Cys Xaa Asp Tyr Thr Xaa Xaa Cys Ser His Ala His Xaa Cys Cys 1 5 10 15 Ser Xaa Asn Cys Tyr Asn Gly His Cys Thr 20 25 37 4 PRT Artificial Sequence Description of Artificial Sequenceconsensus gamma-conopeptide sequence for probe 37 Xaa Cys Cys Ser 1 38 12 DNA Artificial Sequence Description of Artificial Sequencedegenerate probe for consensus gamma-conopeptide sequence. 38 sartgytgya gy 12 39 12 DNA Artificial Sequence Description of Artificial Sequencedegenerate probe for consensus gamma-conopeptide sequence. 39 sartgytgyt cn 12 40 8 PRT Artificial Sequence Description of Artificial Sequenceconsensus pro-gamma-conopeptide sequence for probe. 40 Ile Leu Leu Val Ala Ala Val Leu 1 5 41 24 DNA Artificial Sequence Description of Artificial Sequencedegenerate probe for consensus pro-gamma-conopeptide sequence. 41 athytnytng tngcngcngt nytn 24 42 32 PRT Conus pennaceus PEPTIDE (1)..(31) Xaa at residues 14 and 26 are gamma-carboxyglutamate; Xaa at residue 31 is hdroxy-Pro. 42 Asp Cys Thr Ser Trp Phe Gly Arg Cys Thr Val Asn Ser Xaa Cys Cys 1 5 10 15 Ser Asn Ser Cys Asp Gln Thr Tyr Cys Xaa Leu Tyr Ala Phe Xaa Ser 20 25 30 43 27 PRT Conus textile PEPTIDE (1)..(27) Xaa at residues 9 and 13 are gamma-carboxyglutamate. 43 Cys Gly Gly Tyr Ser Thr Tyr Cys Xaa Val Asp Ser Xaa Cys Cys Ser 1 5 10 15 Asp Asn Cys Val Arg Ser Tyr Cys Thr Leu Phe 20 25 44 8 PRT Conus pennaceus MOD_RES (2) Xaa at residue 2 is carboxymethylCys 44 Asp Xaa Thr Ser Trp Phe Gly Arg 1 5 45 24 PRT Conus pennaceus PEPTIDE (1)..(24) Xaa at residues 6 and 18 are gamma-carboxyglutamate; Xaa at residue 23 is hydroxy-Pro. 45 Xaa Thr Val Asn Ser Xaa Xaa Xaa Ser Asn Ser Xaa Asp Gln Thr Tyr 1 5 10 15 Xaa Xaa Leu Tyr Ala Phe Xaa Ser 20 46 18 DNA Artificial Sequence Description of Artificial Sequenceprimer for M13 universal priming site. 46 tttcccagtc acgacgtt 18 47 19 DNA Artificial Sequence Description of Artificial Sequenceprimer for M13 reverse priming site. 47 cacacaggaa acagctatg 19 

What is claimed is:
 1. A substantially pure conopeptide selected from the group consistng of: (a) PnVIIA: Asp-Cys-Thr-Ser-Xaa₁-Phe-Gly-Arg-Cys-Thr-Val-Asn-Ser-Xaa₂-Cys-Cys-Ser-Asn-Ser-Cys-Asp-Gln-Thr-Tyr-Cys-Xaa₂-Leu-Tyr-Ala-Phe-Xaa₃-Ser (SEQ ID NO:6) wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group; (b) Tx6.4: Xaa₁-Leu-Xaa₂-Cys-Ser-Val-Xaa₁-Phe-Ser-His-Cys-Thr-Lys-Asp-Ser-Xaa₂-Cys-Cys-Ser-Asn-Ser-Cys-Asp Gln-Thr-Tyr-Cys-Thr-Leu-Met-Xaa₃-Xaa₃-Asp-Xaa₁ (SEQ ID NO:7) wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group; (c) Tx6.9: Xaa₁-Xaa₁-Arg-Xaa₁-Gly-Gly-Cys-Met-Ala-Xaa₁-Phe-Gly-Leu-Cys-Ser-Arg-Asp-Ser-Xaa₂-Cys-Cys-Ser-Asn-Ser-Cys-Asp-Val-Thr-Arg-Cys-Xaa₂-Leu-Met-Xaa₃-Phe-Xaa₃-Xaa₃-Asp-Xaa₁ (SEQ ID NO:8) wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group; (d) Tx6.6: Asp-Xaa₁-Xaa₁-Asp-Asp-Gly-Cys-Ser-Val-Xaa₁-Gly-Xaa₃-Cys-Thr-Val-Asn-Ala-Xaa₂-Cys-Cys-Ser-Gly-Asp-Cys-His-Xaa₁-Thr-Cys-Ile-Phe-Gly-Xaa₁-Xaa₂-Val (SEQ ID NO:10) wherein is Xaa₁ is Trp, Xaa₂ is γGlu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group; (e) Gm6.7: Xaa₂-Cys-Arg-Ala-Xaa₁-Tyr-Ala-Xaa₃-Cys-Ser-Xaa₃-Gly-Ala-Gln-Cys-Cys-Ser-Leu-Leu-Met-Cys-Ser-Lys-Ala-Thr-Ser-Arg-Cys-Ile-Leu-Ala-Leu (SEQ ID NO:12) wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group; (f) Mr6.1: Asn-Gly-Gln-Cys-Xaa₂-Asp-Val-Xaa₁-Met-Xaa₃-Cys-Thr-Ser-Asn-Xaa₁-Xaa₂-Cys-Cys-Ser-Leu-Asp-Cys-Xaa₂-Met-Tyr-Cys-Thr-Gln-Ile (SEQ ID:13) wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus is amidated; (g) Mr6.2: Cys-Gly-Gly-Xaa₁-Ser-Thr-Tyr-Cys-Xaa₂-Val-Asp-Xaa₂-Xaa₂-Cys-Cys-Ser-Xaa₂-Ser-Cys-Val-Arg-Ser-Tyr-Cys-Thr-Leu-Phe (SEQ ID NO:14) wherein Xaa₁ is Trp, Xaa₂ is γ-Glu and the C-terminus is amidated; and (h) Mr6.3: Asn-Gly-Gly-Cys-Lys-Ala-Thr-Xaa₁-Met-Ser-Cys-Ser-Ser-Gly-Xaa₁-Xaa₂-Cys-Cys-Ser-Met-Ser-Cys-Asp-Met-Try-Cys (SEQ ID NO:15) wherein Xaa₁ is Trp, Xaa₂ is γ-Glu and the C-terminus is amidated.
 2. The conopeptide of claim 1, wherein the conopeptide is PnVIIA (SEQ ID NO:6) and wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group.
 3. The conopeptide of claim 1, wherein the conopeptide is Tx6.4 (SEQ ID NO:7) and wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group.
 4. The conopeptide of claim 1, wherein the conopeptide is Tx6.9 (SEQ ID NO:8) and wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group.
 5. The conopeptide of claim 1, wherein the conopeptide is Tx6.6 (SEQ ID NO: 10) and wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group.
 6. The conopeptide of claim 1, wherein the conopeptide is Gm6.7 (SEQ ID NO:12) and wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus has a free carboxyl group.
 7. The conopeptide of claim 1, wherein the conopeptide is Mr6.1 (SEQ ID NO:13) and wherein Xaa₁ is Trp, Xaa₂ is γ-Glu, Xaa₃ is Hyp and the C-terminus is amidated.
 8. The conopeptide of claim 1, wherein the conopeptide is Mr6.2 (SEQ ID NO:14) and wherein Xaa₁ is Trp, Xaa₂ is γ-Glu and the C-terminus is amidated.
 9. The conopeptide of claim 1, wherein the conopeptide is Mr6.3 (SEQ ID NO: 15) and wherein Xaa₁ is Trp, Xaa₁ is γ-Glu and the C-terminus is amidated. 